The invention relates in general to firearms and in particular to a new and useful gun barrel with a traction field profile (Zug-Feld-Profil) whose rifling pattern builds on the law of the parabolic rifling curve y=A+Bx+Cx.sup.2.
The rifling pattern of gun barrels is fixed according to the particular requirements, as for example flight stability of the projectiles and strain of the gun barrels and of the driving bands of projectiles. From "Waffentechnisches Taschenbuch", Rheinmetall, 1980, pages 523 to 529, several types of rifling and the curve of the ridge force (Leistenkraft) versus the projectile path in the gun barrel are known. The types of rifling more frequently used are constant rifling, parabolic rifling, and circular rifling. All these types, however, have a variety of disadvantages. Constant rifling has a strong ridge force or guide force rise with the disadvantage of high load on the driving bands and on the projectiles at the start of motion in the gun barrel. This is caused by the fact that the ridge force maximum is located at the point of maximum gas pressure. In progressive rifling, which includes both the parabolic and the circular rifling, the ridge force maximum occurs at the mouth of the gun barrel, with adverse effect on the exit ballistics of the projectiles. Often a constant rifling is appended to the progressive rifling, in order thus to reduce the ridge forces in this zone. At the interfaces between progressive and constant rifling, however, jumps occur in the shape of the ridge force curve, again with an adverse effect due to the wear of the gun barrel.
As is made clear in particular by FIG. 1137, page 525, in "Waffentechnisches Taschenbuch", Rheinmetall, 1980, with constant rifling the ridge force maximum occurs at the point of the gas pressure maximum. The sharp ridge force increase immediately at the beginning of projectile motion has the result that besides the high load of the driving band and of the projectile the powder gases are very hot in this region and thereby the barrel erosion is greatly accelerated. With parabolic rifling, on the contrary, there is less stress on the projectile and driving bands at the start of motion. The ridge force rise has a relatively flat slope. However, as the projectile leaves the gun barrel, high ridge forces act on the barrel mouth, thereby adversely effecting the accuracy of fire.